Preparation of ethambutol–copper(II) complex and fabrication of PVC based membrane potentiometric sensor for copper

Copper(II) complex of ethambutol (I) was prepared and used in the fabrication of Cu2+ selective ISE membrane. The membrane having Cu(II)–ethambutol complex (I) as electroactive material, along with sodium tetraphenylborate (NaTPB) as anion discriminator, dioctylphthalate (DOP) as plasticizer in poly(vinyl chloride) (PVC) matrix in the percentage ratio 6:2:190:200 (I:NaTPB:DOP:PVC) (w/w) gave a linear response in the concentration range 7.94×10−6 to 1.0×10−1 M of Cu2+ with a slope of 29.9±0.2 mV per decade of activity and a fast response time of 11±2 s. The sensor works well in the pH range 2.1–6.3 and could be satisfactorily used in presence of 40% (v/v) methanol, ethanol and acetone and is selective for copper over a large number of cations with slight interference from Na+ and Co2+ if present at a level ⩾1.5×10−5 and 6.5×10−5 M, respectively. It works well over a period of 6 months and can also be used as indicator electrode for the end point determination in the potentiometric titration of Cu2+ against EDTA as well as in the determination of Cu2+ in real samples.